(a) Field of the Invention
The invention relates to the art of electrometallurgy, and more specifically, to apparatus for producing heavy ingots by the electroslag casting, i.e. by casting through a layer of molten slag electrically heated by non-consumable electrodes. The apparatus is particularly suited for the portionwise electroslag casting of heavy (over 15 tons) steel ingots.
(b) Description of the Prior Art
The method of portionwise electroslag casting according to which liquid metal is poured portionwise into a mould has solved the problem of producing heavy ingots with minimum structural defects. However, it is extremely difficult to achieve the requisite chemical composition of ingots obtained from the equipment intended for practising said method because of lack of adequate means for protecting the metal from the oxidizing action of the ambient air. In addition, power consumption of such equipment must of necessity be rather high to compensate for great heat losses.
Known in the art is an apparatus for the electroslag casting of heavy ingots comprising a mould mounted on a bottom plate, a liquid metal pouring system in communication with the melting chamber defined by the cooled walls of the mould and by the bottom plate, and non-consumable electrodes arranged around the circumference of the melting chamber for vertical movement and electrically connected to a power source (e.g., see the prospectus of E. O. Paton Electric Welding Institute "Portsionnaya elektroshlakovaya otlivka slitkov", "Reklama" Publishing House, Kiev, 1976).
The melting chamber of said apparatus is open, which results in:
(a) high heat losses through radiation of the slag pool surface which in turn, is responsible for a higher power consumption to maintain the requisite heating temperature and for an increased wear of metal parts of the apparatus caused by overheating; PA1 (b) oxidizing action of the air on liquid metal and possibility of contamination thereof by other gases, e.g. hydrogen; PA1 (c) dangerous working conditions for operators caused by sputtering as the metal is poured into the mould and by liberation of harmful gases formed in the electroslag process.